Assertion: Alkylbenzene is not prepared by Friedel-Crafts alkylation of benzene.
Reason: Alkyl halides are less reactive than acyl halides.

Which of the following statements about the $S_{N}2$ reaction mechanism is/are true?

For the reactions given below:
$(I)$ Cyclohexyl chloride $\rightarrow$ Cyclohexyl cation + $Cl^-$,$\Delta H_1^{\circ}$
$(II)$ Cyclohex$-2-$enyl chloride $\rightarrow$ Cyclohex$-2-$enyl cation + $Cl^-$,$\Delta H_2^{\circ}$
$(III)$ Benzyl chloride $\rightarrow$ Benzyl cation + $Cl^-$,$\Delta H_3^{\circ}$
$(IV)$ Chlorobenzene $\rightarrow$ Phenyl cation + $Cl^-$,$\Delta H_4^{\circ}$
The correct decreasing order of enthalpies of reaction for producing the carbocation is:

The compound having the longest $C-Cl$ bond is:

Identify the products of the given reactions.

Which reaction is useful for the exchange of halogen in alkyl chloride by iodide?